1. Field of the Invention
The present invention relates to a circuit arrangement for igniting gas discharge flash tubes, and more particularly to a circuit arrangement of the type having at least two main electrodes and connected in parallel with a pulse forming network which is constituted by a chargeable flash capacitor and discharge current limiting inductor.
2. Description of the Prior Art
U.S. Pat. No. 4,070,601 discloses a circuit arrangement for igniting at least one gas discharge flash tube having two main electrodes which are arranged in parallel with a chargeable flash capacitor and at least one electronic switch and are connected to a voltage generator which supplies ignition high frequency (HF) voltage pulses. The electronic switch, likewise, is constituted by at least one gas discharge vessel.
A circuit arrangement of the above type is characterized, in particular, in that the at least one additional gas discharge vessel, which is connected in the discharge circuit in series with the gas discharge flash tube, and which is designed for high forward currents, high blocking voltages and ignition HF voltage pulses of both polarities, can operate on the flash tube and on the at least one gas discharge vessel.
Ignition reliability of this arrangement depends on a statistical distribution of an average delay time of a breakthrough of all gas discharge vessels in the discharge circuit. Moreover, this arrangement simultaneously utilizes up to 5 gas discharge vessels, each of which has a specific level of breakthrough voltage.
In accordance with the teachings of said U.S. patent, the ignition generator has a low impedance, in particular a low inductance, so that the ignition pulses which it supplies, at least adiabatically, heat the gas discharge paths. The energy is supplied within a period of time such that the plasma filament is unable to return to the environment any part of the energy worthy of note, due to heat conduction and radiation losses. For instance, in order to obtain a channel having a resistance of 1 Ohm under normal flash conditions, the obtained channel must be supplied with a quantity of energy in the order of 1000 .mu.W within an interval of time less than 1 .mu.Sec.